The present invention relates to a clutch cover assembly, particularly to a clutch cover assembly including an elastic member for engaging a pressure plate to a flywheel.
The clutch cover assembly is fixed to a flywheel of the engine for transmitting driving force of the engine to a transmission side. The clutch cover assembly is mainly composed of a clutch cover fixed to the flywheel, a pressure plate within the clutch cover for clamping friction materials of a clutch disc between the flywheel and itself, and an elastic member for engaging the pressure place with the flywheel.
Generally, a diaphragm spring is used as the elastic member. This kind of diaphragm spring applies an engaging load on the pressure plate. The diaphragm spring must have a certain level of rigidity in order to function as a lever member which makes it difficult to obtain desirable engaging loads. That is, as shown in FIG. 12, as rigidity of the diaphragm spring becomes higher, allowable deflection (wear allowance) B becomes narrower and load fluctuation C becomes larger. In FIG. 12, an axis of abscissa is deflection S, an axis of ordinate is engaging load P, and the initial set load is shown as load A.
A clutch cover assembly is known in which a lever function and an engaging function are done separately. For example, a separate engaging member such as a coil spring or a washer-type spring is located within the clutch cover so as to apply an engaging force on the pressure plate.
In the clutch cover assembly mentioned above, it is difficult to obtain preferable load characteristics. That is, the allowable deflection is not large enough and the load fluctuation is too large, thus creating the peak mentioned above in FIG. 12. Particularly if a washer-type spring is employed, deflection is small with respect to load because it is difficult to ensure enough room for the washer type spring in the clutch cover.